crypto/aes/aes_cfb.c

/* crypto/aes/aes_cfb.c -*- mode:C; c-file-style: "eay" -*- */
/* ====================================================================
 * Copyright (c) 1998-2002 The OpenSSL Project.  All rights reserved.
 *
 * Redistribution and use in source and binary forms, with or without
 * modification, are permitted provided that the following conditions
 * are met:
 *
 * 1. Redistributions of source code must retain the above copyright
 *    notice, this list of conditions and the following disclaimer.
 *
 * 2. Redistributions in binary form must reproduce the above copyright
 *    notice, this list of conditions and the following disclaimer in
 *    the documentation and/or other materials provided with the
 *    distribution.
 *
 * 3. All advertising materials mentioning features or use of this
 *    software must display the following acknowledgment:
 *    "This product includes software developed by the OpenSSL Project
 *    for use in the OpenSSL Toolkit. (http://www.openssl.org/)"
 *
 * 4. The names "OpenSSL Toolkit" and "OpenSSL Project" must not be used to
 *    endorse or promote products derived from this software without
 *    prior written permission. For written permission, please contact
 *    openssl-core@openssl.org.
 *
 * 5. Products derived from this software may not be called "OpenSSL"
 *    nor may "OpenSSL" appear in their names without prior written
 *    permission of the OpenSSL Project.
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 * 6. Redistributions of any form whatsoever must retain the following
 *    acknowledgment:
 *    "This product includes software developed by the OpenSSL Project
 *    for use in the OpenSSL Toolkit (http://www.openssl.org/)"
 *
 * THIS SOFTWARE IS PROVIDED BY THE OpenSSL PROJECT ``AS IS'' AND ANY
 * EXPRESSED OR IMPLIED WARRANTIES, INCLUDING, BUT NOT LIMITED TO, THE
 * IMPLIED WARRANTIES OF MERCHANTABILITY AND FITNESS FOR A PARTICULAR
 * PURPOSE ARE DISCLAIMED.  IN NO EVENT SHALL THE OpenSSL PROJECT OR
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 * STRICT LIABILITY, OR TORT (INCLUDING NEGLIGENCE OR OTHERWISE)
 * ARISING IN ANY WAY OUT OF THE USE OF THIS SOFTWARE, EVEN IF ADVISED
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/* Copyright (C) 1995-1998 Eric Young (eay@cryptsoft.com)
 * All rights reserved.
 *
 * This package is an SSL implementation written
 * by Eric Young (eay@cryptsoft.com).
 * The implementation was written so as to conform with Netscapes SSL.
 *
 * This library is free for commercial and non-commercial use as long as
 * the following conditions are aheared to.  The following conditions
 * apply to all code found in this distribution, be it the RC4, RSA,
 * lhash, DES, etc., code; not just the SSL code.  The SSL documentation
 * included with this distribution is covered by the same copyright terms
 * except that the holder is Tim Hudson (tjh@cryptsoft.com).
 *
 * Copyright remains Eric Young's, and as such any Copyright notices in
 * the code are not to be removed.
 * If this package is used in a product, Eric Young should be given attribution
 * as the author of the parts of the library used.
 * This can be in the form of a textual message at program startup or
 * in documentation (online or textual) provided with the package.
 *
 * Redistribution and use in source and binary forms, with or without
 * modification, are permitted provided that the following conditions
 * are met:
 * 1. Redistributions of source code must retain the copyright
 *    notice, this list of conditions and the following disclaimer.
 * 2. Redistributions in binary form must reproduce the above copyright
 *    notice, this list of conditions and the following disclaimer in the
 *    documentation and/or other materials provided with the distribution.
 * 3. All advertising materials mentioning features or use of this software
 *    must display the following acknowledgement:
 *    "This product includes cryptographic software written by
 *     Eric Young (eay@cryptsoft.com)"
 *    The word 'cryptographic' can be left out if the rouines from the library
 *    being used are not cryptographic related :-).
 * 4. If you include any Windows specific code (or a derivative thereof) from
 *    the apps directory (application code) you must include an acknowledgement:
 *    "This product includes software written by Tim Hudson (tjh@cryptsoft.com)"
 *
 * THIS SOFTWARE IS PROVIDED BY ERIC YOUNG ``AS IS'' AND
 * ANY EXPRESS OR IMPLIED WARRANTIES, INCLUDING, BUT NOT LIMITED TO, THE
 * IMPLIED WARRANTIES OF MERCHANTABILITY AND FITNESS FOR A PARTICULAR PURPOSE
 * ARE DISCLAIMED.  IN NO EVENT SHALL THE AUTHOR OR CONTRIBUTORS BE LIABLE
 * FOR ANY DIRECT, INDIRECT, INCIDENTAL, SPECIAL, EXEMPLARY, OR CONSEQUENTIAL
 * DAMAGES (INCLUDING, BUT NOT LIMITED TO, PROCUREMENT OF SUBSTITUTE GOODS
 * OR SERVICES; LOSS OF USE, DATA, OR PROFITS; OR BUSINESS INTERRUPTION)
 * HOWEVER CAUSED AND ON ANY THEORY OF LIABILITY, WHETHER IN CONTRACT, STRICT
 * LIABILITY, OR TORT (INCLUDING NEGLIGENCE OR OTHERWISE) ARISING IN ANY WAY
 * OUT OF THE USE OF THIS SOFTWARE, EVEN IF ADVISED OF THE POSSIBILITY OF
 * SUCH DAMAGE.
 *
 * The licence and distribution terms for any publically available version or
 * derivative of this code cannot be changed.  i.e. this code cannot simply be
 * copied and put under another distribution licence
 * [including the GNU Public Licence.]
 */

#ifndef AES_DEBUG
# ifndef NDEBUG
#  define NDEBUG
# endif
#endif
#include <assert.h>

#include <openssl/aes.h>
#include "aes_locl.h"
#include "e_os.h"

/*
 * The input and output encrypted as though 128bit cfb mode is being used.
 * The extra state information to record how much of the 128bit block we have
 * used is contained in *num;
 */

void AES_cfb128_encrypt(const unsigned char *in, unsigned char *out,
                        const unsigned long length, const AES_KEY *key,
                        unsigned char *ivec, int *num, const int enc)
{

    unsigned int n;
    unsigned long l = length;
    unsigned char c;

    assert(in && out && key && ivec && num);

    n = *num;

    if (enc) {
        while (l--) {
            if (n == 0) {
                AES_encrypt(ivec, ivec, key);
            }
            ivec[n] = *(out++) = *(in++) ^ ivec[n];
            n = (n + 1) % AES_BLOCK_SIZE;
        }
    } else {
        while (l--) {
            if (n == 0) {
                AES_encrypt(ivec, ivec, key);
            }
            c = *(in);
            *(out++) = *(in++) ^ ivec[n];
            ivec[n] = c;
            n = (n + 1) % AES_BLOCK_SIZE;
        }
    }

    *num = n;
}

/*
 * This expects a single block of size nbits for both in and out. Note that
 * it corrupts any extra bits in the last byte of out
 */
void AES_cfbr_encrypt_block(const unsigned char *in, unsigned char *out,
                            const int nbits, const AES_KEY *key,
                            unsigned char *ivec, const int enc)
{
    int n, rem, num;
    unsigned char ovec[AES_BLOCK_SIZE * 2];

    if (nbits <= 0 || nbits > 128)
        return;

    /* fill in the first half of the new IV with the current IV */
    memcpy(ovec, ivec, AES_BLOCK_SIZE);
    /* construct the new IV */
    AES_encrypt(ivec, ivec, key);
    num = (nbits + 7) / 8;
    if (enc)                    /* encrypt the input */
        for (n = 0; n < num; ++n)
            out[n] = (ovec[AES_BLOCK_SIZE + n] = in[n] ^ ivec[n]);
    else                        /* decrypt the input */
        for (n = 0; n < num; ++n)
            out[n] = (ovec[AES_BLOCK_SIZE + n] = in[n]) ^ ivec[n];
    /* shift ovec left... */
    rem = nbits % 8;
    num = nbits / 8;
    if (rem == 0)
        memcpy(ivec, ovec + num, AES_BLOCK_SIZE);
    else
        for (n = 0; n < AES_BLOCK_SIZE; ++n)
            ivec[n] = ovec[n + num] << rem | ovec[n + num + 1] >> (8 - rem);

    /* it is not necessary to cleanse ovec, since the IV is not secret */
}

/* N.B. This expects the input to be packed, MS bit first */
void AES_cfb1_encrypt(const unsigned char *in, unsigned char *out,
                      const unsigned long length, const AES_KEY *key,
                      unsigned char *ivec, int *num, const int enc)
{
    unsigned int n;
    unsigned char c[1], d[1];

    assert(in && out && key && ivec && num);
    assert(*num == 0);

    for (n = 0; n < length; ++n) {
        c[0] = (in[n / 8] & (1 << (7 - n % 8))) ? 0x80 : 0;
        AES_cfbr_encrypt_block(c, d, 1, key, ivec, enc);
        out[n / 8] =
            (out[n / 8] & ~(1 << (7 - n % 8))) | ((d[0] & 0x80) >> (n % 8));
    }
}

void AES_cfb8_encrypt(const unsigned char *in, unsigned char *out,
                      const unsigned long length, const AES_KEY *key,
                      unsigned char *ivec, int *num, const int enc)
{
    unsigned int n;

    assert(in && out && key && ivec && num);
    assert(*num == 0);

    for (n = 0; n < length; ++n)
        AES_cfbr_encrypt_block(&in[n], &out[n], 8, key, ivec, enc);
}